What causes mumps?

Who gets mumps?

Mumps, which is extremely common in the rest of the world, is now very uncommon
in the United States. Prior to the introduction of the vaccine in 1967, there were
more than 150,000 reported cases each year in the United States. Since the routine
immunization of children with the mumps vaccine, the occurrence of mumps is very
low. In 1998, there were only 606 cases reported in the United States.

Mumps is highly contagious, and it has historically caused large outbreaks. Today,
mumps is usually seen in persons who have not received the vaccine.

How does the mumps virus cause disease?

The mumps virus is transmitted from person-to-person by direct contact or by contaminated
secretions of the nose and the mouth. Mumps causes an infection in the salivary
glands and in the lining of the mouth. It then spreads throughout the body, and,
sometimes, it causes inflammation in other glands of the body, including the testes
in males and the ovaries in females.

What are the common findings?

After an incubation period of usually 12 to 25 days, the first sign of illness is
usually a fever. Swelling and tenderness of the parotid salivary glands ("parotitis")
occasionally develop within a day after the onset of the fever. Fatigue, poor appetite,
abdominal pain, and headache may accompany these symptoms. The parotid gland, the
largest of the salivary glands, is found at the angle of the jaw. Parotid swelling
with mumps is usually visible, and it is accompanied by tenderness to touch, but
without any overlying redness. Normally, the parotid gland cannot be felt, but it
can be felt if mumps parotitis is present. Patients who develop parotitis may have
tender salivary glands, with the greatest symptoms after 1 to 3 days, and then the
symptoms gradually subside after about 6 to 10 days.

Approximately 30% of post-pubertal males with the mumps infection develop inflammation
of the testes ("orchitis"). Approximately 5% of post-pubertal females occasionally
develop inflamed ovaries ("oophoritis").

Mumps can cause viral meningitis that is usually mild and resolves with complete
recovery in three to four days.

How is mumps diagnosed?

Mumps usually is diagnosed on the basis of fever and the finding of parotid gland
swelling. There is a specific antibody test for mumps that can be used to confirm
the infection, but this requires obtaining blood at two time points, two to four
weeks apart, to test for the development of mumps antibodies.

How is mumps treated?

There is no specific treatment for mumps. Antibiotics are not helpful because a
virus causes mumps. The disease usually is mild with complete recovery. Some children
may require hospitalization for intravenous fluids. Fever and pain should be treated
with acetaminophen or ibuprofen. Bed rest and pain medications may be necessary
for orchitis until the symptoms resolve, which is usually within several days, but,
occasionally, may persist for two to three weeks.

What are the complications?

The possibility of mumps orchitis causes unnecessary anxiety in many men concerned
about testicular atrophy and sterility. However, most cases of mumps orchitis involve
only one testicle that does not lead to sterility. Sterility from mumps is rare
even when both testicles are involved. Some degree of testicular shrinkage may be
detectable after the mumps infection; however, it does not cause sterility. Impotence
does not result from mumps.

How can mumps be prevented?

Mumps is effectively prevented by the routine administration of the mumps vaccine,
usually given as Measles-Mumps-Rubella (MMR) vaccines to all children, which is
recommended beginning at 12 months of age. A single dose of the mumps vaccine results
in protection of approximately 95% of children. A second dose of MMR is recommended
at four to six years of age. It is not a problem if another dose of the mumps vaccine
is given in addition to the two recommended doses.

The spread of mumps can be prevented by minimizing exposure to children who have
symptoms of the disease, and by good handwashing after exposure to the disease.

What research is being done?

Because mumps is now extremely uncommon, and because the vaccine is extremely safe
and effective in preventing mumps, there is not much research currently being performed
on this disease. There is some research being performed on the long-term immunity
of the mumps vaccine to confirm that it does provide lifelong immunity.

Dr. Jenson graduated from George Washington University School of Medicine in Washington,
DC.

He also completed a residency in pediatrics at the Rainbow Babies and Children's
Hospital of Case Western Reserve University in Cleveland, Ohio, and a fellowship
in pediatric infectious diseases and epidemiology at Yale University School of Medicine.

Dr. Jenson has an active research program on the biology of Epstein-Barr virus and
other human and non-human primate herpes viruses.

He is active in the general pediatric and infectious diseases teaching and clinical
activities of his Department and Division, is a co-editor of Nelson Textbook of
Pediatrics and of Pediatric Infectious Diseases: Principles and Practice, and authors
the book Pocket Guide to Vaccination and Prophylaxis.

Charles T. Leach, M.D.

Dr. Leach received his medical degree at the University of Utah School of Medicine
and completed his pediatrics residency as well as a fellowship in pediatric infectious
diseases at UCLA.

He is currently Associate Professor and Director of Research in the Department of
Pediatrics at the University of Texas Health Science Center at San Antonio.

Dr. Leach conducts scientific research in the areas of herpes virus infections,
pediatric AIDS, and infectious diseases among residents of the Texas-Mexico border.